The present invention relates to a fluidic device comprising a plurality of fluidic modules, and a passage block to which the plurality of fluidic modules are connected and which is provided, in its inside, with fluid passages for communicating the plurality of fluidic modules with one another.
For example, a device as shown in FIGS. 9, 10 and 11 is known as a background-art fluidic device. The device comprises a plurality of fluidic modules such as a fluid pump not shown, a tank not shown, a fluid-controlled valve 11 and an actuator 12, and a passage block 13 to which the fluid pump, the tank, the fluid-controlled valve 11, and the actuator are attached. The passage block 13 is provided, in its inside, with four fluid passages. That is, in the passage block 13, there are provided a feed passage 14 for connecting the fluid pump and the fluid-controlled valve 11 to each other, an exhaust passage 17 for connecting the tank and the fluid-controlled valve 11 to each other, a head-site feed and exhaust passage 17 for connecting the fluid-controlled valve 11 and a head-site chamber 16 of the actuator 12 to each other, and a rod-site feed and exhaust chamber 19 for connecting the fluid-controlled valve 11 and a rod-site chamber 18 of the actuator 12 to each other.
Incidentally, the feed passage 14, the exhaust passage 15 and the feed and exhaust passages 17 and 19 are bent meanderingly because both ends of each passage is generally not on one and the same axis. Taking the rod-site feed and exhaust passage 19 as an example, the passage 19 is bent three times because the passage 19 has a first passage portion 19a extending downward from an upper surface of the passage block 13, a second passage portion 19b extending backward from a lower end of the first passage portion 19a, a third passage portion 19c extending leftward from, an intermediate portion of the second passage portion 19b, and a fourth passage portion 19d extending downward from an intermediate portion of the third passage portion 19c. Further, an opening end of an intermediately located passage portion (straight hole) such as the second passage portion 19b is closed by a plug 23 which has, as shown in FIG. 12, a body 20 inserted from its forward end side into the opening end portion of the second passage portion 19b, a hole 21 formed in the body 20, and a plug 22 implanted in the hole 21 to widen the diameter of a rear end portion of the body 20.
If the fluid passages are bent meanderingly as described above, each fluid passage needs passage portions of the number obtained by addition of one to the number of bends. When, for example, the fluid passage is bent three times, the fluid passage needs four passage portions (straight holes). As a result, there is a problem that the cost of the resulting device is increased because a troublesome drilling process is required as well as the structure of the device is complicated. Moreover, the opening end portion of each intermediate passage portion (straight hole) must be processed with sufficiently high accuracy to be closed by the aforementioned plug 23. As a result, there is also a problem that the cost of the device is increased more greatly. Moreover, stress concentration is apt to occur in each bending portion of the fluid passage, that is, in a joint between adjacent passage portions of the fluid passage because such adjacent passage portions is crossed each other at 90 degrees. To prevent such stress concentration, it is necessary to chamfer each bending portion. As a result, there is a further problem that the cost of the device is increased more and more greatly.